Method of and apparatus for forming parts with re-entrant surfaces

ABSTRACT

A turbine or compressor blade with projections adjacent each end having one or more arcuate re-entrant surfaces is initially forged and is finish formed, either hot or cold, in a mould which defines the aerodynamic portion of the blade. The projections are finish formed by punches and after retraction of the punches, the mould halves are separated by a pivotal movement about an axis which contains the center of curvature of the arcuate re-entrant surfaces thus enabling the formed blade to be removed.

United States Patent Portal [45] Aug. 1, 1972 [54] METHOD OF ANDAPPARATUS FOR [56] References Cited FORMING PARTS WITH RE-ENTRANT UNTTEDSTATES PATENTS SURFACES 2,751,667 6/1956 Gruet en ..29/156.8 [721lnvemo" Bdogne, France 1,910,943 5/1933 Wiberg et al. ..29/l56.8 [73]Assignee: S.A. Forges de Bologne, Bologne,

France v Primary Examiner-Lowell A. Larson Attorney-John Lezdey [22]Filed: Nov. 23, 1970 [57] ABSTRACT [21] Appl 92045 A turbine orcompressor blade with projections adjacent each end having one or morearcuate re-entrant [30] Foreign Application Priority Data surfaces isinitially forged and is finish formed, either hot or cold, in a mouldwhich defines the aerodynamic Dec. 19, 1969 France ..6944249 portion ofthe blade The projections are finish formed by punches and afterretraction of the punches, the [52] US. Cl. ..72/354, 72/357, 72/360mould halves are separated by a pivotal movement [51] Int. Cl. ..B2lj13/02 about an axis which contains the center of curvature [58] Field ofSearch .,72/354, 357, 360, 373, 374, of the arcuate re-entrant surfacesthus enabling the 72/376, 377; 29/l56.8 B; l8/DIG. 58

formed blade to be removed.

2 Claims, 3 Drawing Figures METHOD OF AND APPARATUS FOR FORMING PARTSWITH RE-ENTRANT SURFACES BACKGROUND OF THE INVENTION 1. Field of theInvention.

The present invention relates to a method and apparatus for the finishforming of forged parts having reentrant surfaces.

2. Description of the Prior Art.

There are used in the construction of stators or rotors ofturbo-machines, blades having an aerodynamic profiled portion and whichare connected to one or more crowns or shrouds forming the rim or thehub of the wheel.

Each blade comprises at least one lateral projection or other securingmeans by which it is secured respectively to the rim or to the hub ofthe rotor or stator, the projection comprising arcuate surfaces of whichsome are reentrant.

Previously proposed methods of forging between two matrices or two moldsdo not permit removal from the mold of parts having a re-entrantsurface.

At the present time when forged parts are used, it is necessary tomachine the parts with a machine tool in order to form re-entrantsurfaces on the projections or other securing means.

This method is time-consuming and costly.

SUMMARY OF THE INVENTION According to the present invention there isprovided a method of forming a forged part with at least one reentrantsurface on a projection thereof comprising the steps of confining aforged blank of the part in a space defining the final dimensions of aportion of the forged part, applying pressure to the projection of theblank to form said re-entrant surface, releasing said pressure, andremoving the formed forged part from the space.

Further according to the present invention there is provided a method offinish forming an elongate forged part having a main portion and alateral projection adjacent each end thereof, each said lateralprojection having at least one laterally extending surface of arcuateform, the center of radius of which surfaces lies on the longitudinalaxis of the part, said method comprising the steps of confining a forgedblank of the part in a space defining the final dimensions of the mainportion of the part, said space being defined by mold parts movabletowards and away from one another along an arcuate path the center ofwhich coincides with the center of radius of the laterally extendingarcuate surfaces, applying pressure endwise of the blank to form saidprojections with their arcuate surfaces, releasing said pressure, andmoving the mold parts relatively to one another along said arcuate pathwhereby to release the elongate part in its final dimensions.

Still further according to the present invention there is providedapparatus for finish forming a forged part having at least onere-entrant surface on at least one lateral projection thereof saidapparatus comprising two mold members, each having formed thereindepressions corresponding to a portion of the finishforrned part, and atleast one recess leading to that portion of the depression which definesthe re-entrant surface, means pivotally connecting the mold members, apunch slidable in said recess to engage the projection and form there-entrant surface, a fluid-operated actuator for operating the punch,and means for pivoting the mold parts about an axis containing thecenter of the arcuate surface whereby the finish formed part can beremoved along a corresponding arcuate path.

The method in accordance with the invention, enables the production froma rough blank made in accordance with known forging methods, a part withfinal dimensions.

Moreover, the method in accordance with the invention enables, byavoiding machining the lateral projections, also obviates interruptingthe flow lines in the grain of the metal at the juncture of the profilewith the projections and thus to increase the fatigue stress limit ofthe vanes.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described,by way of example, with reference to the accompanying diagrammaticdrawing, in which:

FIG. 1 is an elevation of a blank produced by forging and before formingin accordance with the present invention;

FIG. 2 is a similar view of the part after forming; and

FIG. 3 is a partially sectioned perspective view of apparatus forforming a part in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A blank is shown in FIG. 1 whichcomprises a blade 1 having an aerodynamic profiled main portion and twolateral projections 2, 3, or other securing means disposed at the endsof the blade I. The projections 2, 3, comprise, respectively, twooptional locating parts 4, 5 in order to facilitate centering of theblade as a whole.

As is shown in FIG. 1, the securing means 2, 3 produced by forging havesurfaces 6, 7, 8, 9 which are only of tapered form, i.e., are notre-entrant.

The method in accordance with the invention enables the production of afinished part as shown in FIG. 2, in which arcuate surfaces 10 of radiusR and center 0 as well as circular faces 11 of radius r and center 0 areof re-entrant form.

The apparatus for carrying out the method is shown in FIG. 3 andincludes two forming members l2, l3 defining a space 14 in which theblank 1, shown in FIG. 1, is located.

The space 14 has a shape that is complementary to that of the finalpart, is open at its two ends and extends into recessed portions l5, 16in which punches 17, 18 are displaceable under the action ofpressure-fluid actuators, the pistons of which 19 and 20 are rigid withthe said punches.

The forming member 12 is pivoted to the member 13 about the axis xx bymeans of pins 21 of which one only is shown in FIG. 3, the said axis xx,being coincident with the center 0 (FIG. 2) for facilitating thedemolding operation.

The part I, when disposed in the space 14 is held between the twoforming members 12, 13 which are held together by locking means of anysuitable form exerting a force acting in a direction as indicated by thearrow F, said punches l7, 18 being slidable as indicated by the arrows Aand B, in the portions 15, 16 of the space 14 under the action ofactuators 19 and 20. The

projections 2 and 3 take up the form defined by the bottom of theportions 15, 16 of the space and the end faces of the punches 17, 18.

The form of the projections thus produced corresponds to that shown inFIG. 2.

Before removal from the mold, the punches 17, 18 are moved apart indirections opposite to the arrows A and B and the forming member 12 ispivoted about the axis xx, in order to free the part 1 from the member13 likewise by an arcuate movement.

Although the method described relates particularly to blades of turbomachines, it is clear that it may be applied to the production of anyparts necessitating removal from a mold by a rotational movement afterforging.

What is claimed is:

1. A method of finish forming an elongate forged part having a mainportion and a lateral projection adjacent each end thereof, each saidlateral projection having at least one laterally extending surface ofarcuate form, the center of radius of which surfaces lies on thelongitudinal axis of the part, said method comprising the steps ofconfining a forged blank of the part in a space defining the finaldimensions of the main portion of the part, said space being defined bymold parts mova ble towards and away from one another along an arcuatepath the center of which coincides with the center of radius of thelaterally extending arcuate surfaces,

applying pressure endwise of the blank to form said projections withtheir arcuate surfaces,

releasing said pressure, and

moving the mold parts relatively to one another along said arcuate pathwhereby to release the elongate part in its final dimensions.

2. Apparatus for finish forming a forged part having at least onere-entrant surface on at least one lateral projection thereof saidapparatus comprising two mold members, each having formed thereindepressions corresponding to a portion of the finish-formed part, and atleast one recess leading to that portion of the depression which definesthe re-entrant surface,

means pivotally connecting the mold members,

a punch slidable in said recess to engage the projection and form there-entrant surface,

a fluid-operated actuator for operating the punch,

and

means for pivoting the mold parts about an axis containing the center ofthe arcuate surface whereby the finish formed part can be removed alonga corresponding arcuate path.

1. A method of finish forming an elongate forged part having a mainportion and a lateral projection aDjacent each end thereof, each saidlateral projection having at least one laterally extending surface ofarcuate form, the center of radius of which surfaces lies on thelongitudinal axis of the part, said method comprising the steps ofconfining a forged blank of the part in a space defining the finaldimensions of the main portion of the part, said space being defined bymold parts movable towards and away from one another along an arcuatepath the center of which coincides with the center of radius of thelaterally extending arcuate surfaces, applying pressure endwise of theblank to form said projections with their arcuate surfaces, releasingsaid pressure, and moving the mold parts relatively to one another alongsaid arcuate path whereby to release the elongate part in its finaldimensions.
 2. Apparatus for finish forming a forged part having atleast one re-entrant surface on at least one lateral projection thereofsaid apparatus comprising two mold members, each having formed thereindepressions corresponding to a portion of the finish-formed part, and atleast one recess leading to that portion of the depression which definesthe re-entrant surface, means pivotally connecting the mold members, apunch slidable in said recess to engage the projection and form there-entrant surface, a fluid-operated actuator for operating the punch,and means for pivoting the mold parts about an axis containing thecenter of the arcuate surface whereby the finish formed part can beremoved along a corresponding arcuate path.